HAM’S LIFE

In the two posts prior to this one I talked about choosing the right solder for amateur radio soldering.  The post just before this discusses the tools needed to solder.  Having the right solder and the right tools still does not get the job done; you have to heat the iron up and apply the solder to get the job done. 

Though I said it before in the earlier post I believe it bears repeating, the two most important elements in getting a good solder connection are cleanliness and proper heat. 

Cleanliness means not only free from dirt, grease, or some other foreign element but it includes free from oxidation. 

When soldering, the parts to receive the solder must reach a high enough temperature to melt the solder.  The molten solder will mix with hot metal down to a few molecules below the surface. If the parts being soldered are copper, the most common metal we solder in electronics, this mixing of molecules results in a thin coat of tin/lead/copper alloy (when using tin/lead solder) forming over the surface receiving the solder.  If it is some other metal that will accept solder then the solder alloys, of course, with the other metal rather.  This process of mixing the molecules on the surface, called the wetting action, happens because liquid solder acts as a solvent that dissolves the metal.      

Solder will not dissolve dirt or metal oxide.  Thus if there is a coat of oxide or dirt on the parts you want to solder it must be removed before the solder will adhere to it.  Flux will not remove oxide.  Most oxides can be removed with an ink eraser but in some instances a fine grit emery cloth may be necessary. 

Soldering aluminum requires some special consideration because aluminum forms a new very durable oxide layer almost as fast as you can remove the old layer.  Thus it does not make a good material to use for learning soldering techniques.

Applying a small amount of liquid rosin flux on the clean surface will prevent oxygen from coming in contact with the metal during the heating process and thus improve the quality of the solder connection. 

When soldering, do not melt the solder with the iron.  Place the tip of the iron on one side of the prepared junction and then touch the opposite side of the junction with the tip of the solder and allow the solder to melt by receiving heat from the parts needing the solder. 

To efficiently transfer the heat from the tip of the soldering iron it must be properly tinned. The term tinned simply means forming a thin layer of solder that covers the working surface of the iron tip.    

Some soldering iron tips come pre-tinned while others do not. Even pre-tinned tips need re-tinning before they are used to insure proper heat transfer.  Tin the tip the first time heat is applied to it just as soon as it heats up sufficiently to do the process. 

To tin an iron wipe the tip across a damp sponge and then place the solder on the tip so a glob of solder covers working surface of the tip; when the solder sufficiently covers the tip wipe off the excess solder on the sponge, a thin layer of solder should remain on the tip.  . 

After tinning the tip and before placing it into the iron holder melt a small glob of solder on the tinned area.  This will protect the tin coat and it will help dissipate some of the heat from the tip to help it last longer.

When you are ready to start soldering, wipe off the excess solder on the damp sponge.  The tip should have a nice bright silver color.

When you are done wipe the tip on the sponge again and recover the tip with solder then return it to its holder. 

Ok now start your soldering iron and get to soldering.  The only way you are going to learn to solder is by soldering.